1. Field of the Invention
This application is directed to apparatuses and methods of providing access to a region of the spine. More particularly, this application is directed to apparatuses and methods that can provide access to upper spinal regions, such as the cervical and thoracic regions, and other similar spinal regions and to procedures that are more easily performed at an angle to the midline of the spine.
2. Description of the Related Art
Spinal surgery presents significant difficulties to the physician attempting to reduce chronic back pain or correct spinal deformities without introducing additional trauma due to the surgical procedure itself. In order to access the vertebrae to perform spinal procedures, the physician is typically required to make large incisions and cut or strip muscle tissue surrounding the spine. In addition, care must be taken not to injure nerve tissue in the area. Consequently, traditional surgical procedures of this type carry high risks of scarring, pain, significant blood loss, and extended recovery times.
Apparatuses for performing minimally invasive techniques have been proposed to reduce the trauma of posterior spinal surgery by reducing the size of the incision and the degree of muscle stripping in order to access the vertebrae. One such apparatus provides a constant diameter cannula that is made narrow in order to provide a small entry profile. As a result, the cannula provides minimal space for the physician to observe the body structures and manipulate surgical instruments in order to perform the required procedures. Many spinal conditions arise in the thoracic and lumbar region of the spine, where spinal anatomy can be approached along a vertical plane parallel to a vertical plane through the spinal mid-line. However, some spinal ailments arise in spinal regions where the approach to the spine is generally at an angle to the midline, e.g., in the cervical region. Also, some lumbar and thoracic procedures are performed generally at an angle to the midline.